Investigation of Plasma Thermal Spray Coatings at OGMA: Addressing Delamination Issues in Aerospace Components

Atmospheric Plasma Spraying (APS) processes are widely employed in the aerospace industry to enhance thermal resistance and durability of critical components. Despite proven advantages, delamination remains a recurring defect, particularly at coated surface edges where interfacial bonding becomes susceptible to irregularities, contamination, and residual stresses.

This phenomenon compromises component qualification for service, increasing costs and reducing reliability. This thesis investigates mechanisms leading to delamination in APS systems and proposes corrective and preventive strategies to mitigate its occurrence. The study combines industrial data analysis, experimental trials, and microstructural evaluations to identify key process variables associated with non-conformities, including interface contamination, roughness non-uniformity, and coating thickness variations beyond specification limits.

Statistical analysis of OGMA’s quality control data reveals delamination rates correlating with specific process parameter deviations, particularly surface preparation inconsistencies. The research analyzed 165 metallographic and mechanical test reports from over 1,363 OGMA records, revealing a 12.1% nonconformity rate with coating thickness deviations representing 38% of failures. The METCO 450NS + XPT268 combination demonstrated highest delamination risk, with 72% of tensile strength failures correlating with oxide cluster presence.

Recommendations include improving surface preparation through frequent abrasive media replacement, controlling roughness uniformity via profilometry, and minimizing material excess using micrometer-based thickness verification. Future proposals encompass robotic automation of surface treatment and predictive quality systems based on in-situ diagnostics. This work, conducted in collaboration with OGMA – Industria Aeron ´ autica de Portugal, S.A., contributes to optimiz- ´ ing plasma spray practices while supporting more sustainable and cost-efficient production frameworks that reduce defect rates and enhance operational lifespan of aerospace components.